As it is well known in this technical field, the use of electronic units for managing the injection in modern automotive engines is now usual procedure. An example of this is provided by the European Patent Application 01830645.6, to the same Applicant.
Their use has been dictated by the need to keep certain engine parameters under control so as to diminish the engine emissions, according to the close limits set by law in many of the industrialized countries.
The leading automotive companies are increasing the production of direct injection engines to comply with such restrictive laws, calling for contaminants being released to the environment in ever decreasing amounts, as well as to raise the level of their engine performance. However, these are engines need a more sophisticated and complex control system.
Recently introduced multiple-injection fuel systems, wherein the parameters to be controlled are characterized by more pressing specifications of time, make the use of a certain number of different-type sensors, whose signals are always processed by current control units, a necessity.
Thus, nowadays these units, commonly known as ECU (Electronic Control Unit), are now called upon to provide control functions of increasing complexity.
In the automotive industry it is common practice to use ECUs equipped with a TPU co-processor (Time Processor Unit) which is specifically operative to process signals coming from a sensor of a drive shaft phonic wheel and from a sensor of a camshaft phonic wheel, thereby to determine the angular position of the drive shaft and the operative phase of the engine.
A big number of parameters must be taken into consideration to carry out the injection process under control by an ECU or a TPU in the best way. This implies a great computational load, both for the ECU and for the co-processor TPU. In fact, both these units handle a large number of signals carrying different priority levels. In all cases, these signals have to be managed by software routine, activated by interrupt signals, in case of the ECU, and by the occurrence of certain events, in case of the TPU.
In either cases, a discrepancy is bound to exist between an ideal time moment for carrying out the injection and the real time when the injection is actually carried out. This will result in incomplete combustion, generating larger pollutant amounts than intended.